Reels, or drums, for storing cables, such as large diameter optical strands or multi-strand communication cables, are generally constructed with axially spaced, wooden side plates, or flanges, that are conjoined by a fiber (paper) or wood-stave core. In the alternative, the reels have been made of steel that has been treated with a rust inhibitor for improved life. The cable is wound onto the reel--usually in lengths of 10,000 feet or more. In preparation for winding the cable onto the reel, one end of the cable is anchored to one side flange of the reel. To anchor the cable to the reel, one end of the cable is typically fed through a slot, or anchor aperture, that penetrates one side flange, or plate, in radially outer proximity to the core, and that end is then stapled, or otherwise secured, to the outer surface of that side flange. The desired amount of cable is then wound onto the core in the space between the side flanges.
Reels, with the cable wound thereon, are then stored for various lengths of time in one or more locations that are subject to changes in ambient conditions. As a result, the cable and the storage reel undergo expansion and contraction in response to changes in the climatic conditions to which they are subjected during this storage period. Reels using wood-stave, or fiber, cores are particularly subject to water absorption and thermal warpage. Specifically, such reels have a high water absorption potential and the resulting warpage causes swelling, and eventual delamination, of the core material. Failure of the core generally requires rewinding of the cable. Thus, reels having either the wood-stave, or fiber, core must be stored in a climatically controlled environment in order to minimize deterioration, which significantly increases the storage cost. Steel reels are generally capable of being stored outdoors, but they are subject to rust when the rust protection wears off.
Some reels having wood-stave cores can be disassembled after the cable is dispensed to reduce the space required for storage or shipment to the winding facility, but generally the means by which those reels are assembled do not readily permit disassembly without adversely affecting the structure of the components from which the reel is made. Although these reels have the lowest original manufacturing cost, they can only be used once. They are generally non-recyclable, and they must be stored in a climatically controlled environment after assembly--and particularly after the cable has been wound thereon.
Historically, the fiber core reels must remain assembled and therefore require more space for storage and shipment to the winding facility. These reels have an original cost of approximately twice the cost of reels having wood-stave cores. They, too, can be used only once, are non-recyclable and must be stored in climatically controlled conditions after assembly and following the winding of a cable thereon.
Steel reels are typically not fabricated to be disassembled and therefore require large storage space. In addition, steel reels have an original cost of from about twenty to about thirty times the cost of the wood-stave reels, but steel reels can be reused. The principal structural drawback to steel reels is that the side flanges require frequent maintenance due to bending and erosion of the rust inhibiting coating.
Cable stored on either the wood-stave core or the fiber core reels is subject to "creep." Creep is defined as the extrusion, or "out-feeding," of cable through the anchor slot. The amount of cable creep is generally between one to one and one-half percent (1 to 1.5%) of the cable length. That length of the cable which is extruded by creep flails about as the reel is rotated to dispense the cable. The flailing cable end can cause damage to vehicles, other equipment and/or personnel in the immediate vicinity. In fact, the prior art reels often have a warning posted thereon which advises the reader of this danger. To minimize the damage that can be inflicted by the flailing cable end, it must be occasionally trimmed, and those trimmed lengths are, therefore, wasted. This problem is sufficiently serious that a worker is generally assigned the task of inspecting for extruded cable and trimming the extruded end, as necessary.
The source of "creep" appears to be the direct result of a low coefficient of friction between the reel core and the cable wound thereon, and/or dissimilar coefficients of thermal expansion between the cable and the real core. Flexing of the wooden staves also appears to contribute to this ubiquitous problem. The commonly employed solution, other than to use the expensive steel reels, is to wind an additional one to one and one-half percent (1 to 1.5%) of the required cable length onto the reel in order to be assured that the customer has the correct amount available, even though there is a significant loss due to creepage and trimming. This approach results in a significant cost increase to the cable company, and their customers, in view of the high cost of cable per unit length.